HR: 1340h
AN: B43B-0260    [Abstracts]
TI: Observed Vegetation-Climate Feedbacks in the United States
AU: * Notaro, M
EM: mnotaro@wisc.edu
AF: Center for Climatic Research UW Madison, 1225 West Dayton Street, Madison, WI 53706 United States
AU: Liu, Z
EM: zliu3@wisc.edu
AF: Center for Climatic Research UW Madison, 1225 West Dayton Street, Madison, WI 53706 United States
AB: Observed vegetation feedbacks on temperature and precipitation are assessed across the United States using satellite-based fraction of photosynthetically active radiation (FPAR) and monthly climate data for the period of 1982-2000. This study represents the first attempt to spatially quantify the observed local impact of vegetation on temperature and precipitation over the United States, for all months and by season. Lead-lag correlations and feedback parameters are computed to determine the regions where vegetation substantially impacts the atmosphere and to quantify this forcing. Temperature imposes a significant instantaneous forcing on FPAR, while precipitation's impact on FPAR is greatest at one-month lead, particularly across the prairie. An increase in vegetation raises the surface air temperature by absorbing additional radiation and, in some cases, masking the high albedo of snow cover. Vegetation generally exhibits a positive forcing on temperature, strongest in spring and particularly across the northern states. The local impact of FPAR on precipitation appears to be spatially inhomogeneous and relatively weak, potentially due to the atmospheric transport of transpired water. The computed feedback parameters can be used to evaluate vegetation-climate interactions simulated by models with dynamic vegetation.
DE: 0400 BIOGEOSCIENCES
DE: 0426 Biosphere/atmosphere interactions (0315)
DE: 0439 Ecosystems, structure and dynamics (4815)
DE: 3322 Land/atmosphere interactions (1218, 1631, 1843)
SC: Biogeosciences [B]
MN: Fall Meeting 2005